John Lewis has apologised to betrothed couples and other users of its gift list website after the service went offline over the weekend.
Visitors were presented with error messages saying that the site's domain registration had expired.
In some cases they were invited to renew the lease themselves.
Organisations typically set active web domains to auto-renew to avoid such problems, but John Lewis says there was an "issue" with renewing its domain.
Several customers had tweeted the business seeking an explanation, and had been told in response that users needed to phone staff while the matter was being addressed.
"Our wedding is on 19 May, and despite only having a week to go a lot of our friends had yet to visit [the site]", bride-to-be Clare Briscoe told the BBC.
"The lack of information from John Lewis was concerning - I had to join Twitter to try to get more information.
"I had a lot of other bits of admin to get done rather than [having to] reassure guests that it would 'probably' be fine.
"I'm happy it seems to be sorted now, but not renewing a domain registration is fairly embarrassing."
PinkNews chief executive Benjamin Cohen was also among those affected.
Tempted to renew @johnlewisretail ‘s domain name for them so that our wedding guests can access our gift list! So ridiculous that they’ve still not worked out how to renew the domain name! pic.twitter.com/NRkAM0ic0z— Benjamin Cohen (@benjamincohen) May 14, 2018
@JLcustserv @johnlewisretail the gift list website is down!?? I just tried adding an item and the website just stopped working. Also had friends and family messaging me to tell me they can’t get on it either.— Samantha Finch (@Samantha__Finch) May 12, 2018
@johnlewisretail trying to go into your gift list website for a friend's wedding registry and it keeps telling me the domains expired and wants me to pay to renew it? Help! Or has it actually lapsed? pic.twitter.com/3EhTJD8dCQ— Helana Malone (@gammygambo) May 13, 2018
The WhoIs database indicates that johnlewisgiftlist.com's domain registration expired last Thursday, but was subsequently renewed on Sunday to run until 2021.
"We would like offer our sincerest apologies to customers who have experienced difficulties accessing our gift list website," said a spokeswoman for the business.
"There was an issue renewing the domain name which has been fixed and most customers can once again access the site - though it may take a few more hours for some internet providers to update."